The invention relates to a weighing apparatus for grading articles such as eggs, tomatoes and the like according to their weight class, which apparatus includes a tray member movable under the load of an article a distance dependent on article weight, and means for sensing the deflected distance to determine the article's grade.
In a similar apparatus known from Dutch patent application No. 65,01016 each weighing apparatus determines exclusively whether a certain weight is exceeded. In this connection each time a number of weighing apparatus is arranged one behind the other and the article has to be weighed by one or more weighing apparatuses depending on its weight till it reaches the weighing apparatus which tips by the weight of the article, after which said article is moved away. Furthermore, in this prior apparatus for producing the resetting force use is made of spring plates which are relatively rigid in order to achieve rapid weighing, which rigidity is objectionable in that no accurate weighing is obtained.
Other prior art structures are shown in U.S. Pat. Nos. 3,068,948 and 3,390,733 (see FIGS. 3, 6 and 8 in particular). While such structures are useful for grading articles such as eggs and the like, they normally require a large number of moving parts, and a complicated structural arrangement. According to the present invention, on the other hand, a greatly simplified apparatus is provided for performing the same ultimate function.
According to the present invention, a tray for receiving an article is mounted for generally up and down movement by a plurality of leaf springs operatively connected to the tray and a stationary support, which leaf springs, in addition to mounting the tray for movement, also provide a restoring force that is load dependent -- that is the leaf springs allow deflection of the tray a first distance dependent upon the weight of the article received thereby. The provision of a single means to provide both these functions eliminates a large amount of the cumbersome apparatus inherent in prior art devices, while still allowing the ultimate grading function to be performed just as well.
The tray will, if not restricted, deflect downwardly a first distance in response to the load thereon. In order to provide for grading of the article, however, means are provided for allowing generally downward deflection of the tray relative to the support member for the leaf springs only to a second distance, normally less than the first distance. Such means may be in the form of a stationary or a movable stop. Means are provided for gradually changing the relative position of the stop and the support member so that the second distance approaches (and ultimately surpasses) the first distance. Such means preferably take the form of an out-of-round cam or the like. A cam follower for the cam is operatively connected to the support or the stop, and in response to rotation of the cam, provides for relative movement therebetween. Means are also provided for sensing when the second distance is substantially equal to the first distance, such as electrical contacts or photoelectric apparatus.
When the first distance substantially equals the second distance, the sensing means is actuated, and additionally other means may be actuated for recording the position of the cam at the time the second distance substantially equals the first distance for determining the grade of the article. Dependent upon the grade so sensed, the article may then be passed on to one of a number of separate storage or grading bins, packing apparatus, or the like. Other means, such as an electrical interlock, can also be provided to insure that the cam position recording means is actuated only once during each complete weighing cycle, or complete revolution of the cam.
It is the primary object of the present invention to provide a simplified apparatus for article weight-grading. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.